CN101226352B

CN101226352B - Image forming apparatus and method of controlling the same

Info

Publication number: CN101226352B
Application number: CN2007103062442A
Authority: CN
Inventors: 朴秀哲; 姜范权
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2006-12-22
Filing date: 2007-12-20
Publication date: 2010-12-01
Anticipated expiration: 2027-12-20
Also published as: US20080152365A1; KR20080058780A; KR101305979B1; CN101226352A

Abstract

The present invention provides an image forming apparatus and a method of controlling the same, which control a paper pickup-related time to perform duplex printing. The apparatus includes a first conveyance path, a second conveyance path, a counter, and a controller. A paper feed unit and a paper exit unit are provided in the first conveyance path where development, transfer, and fusing processes are performed. In the second conveyance path, paper is conveyed separately from the first conveyance path. The counter measures a conveyance period of time, during which a sheet of paper is conveyed along the second conveyance path, based on a sensing signal from a paper feed sensor and a paper exit sensor. The controller controls a paper pickup-related time to perform duplex printing according to the difference between the conveyance period of time measured by the counter and a reference period of time.

Description

Imaging device and control method thereof

Technical field

This total inventive concept relates to a kind of imaging device and control method thereof, and relates more specifically to a kind of control paper pick-up (pickup) imaging device and the control method thereof of correlation time to carry out duplex printing.

Background technology

A plurality of transfer rollers that provide along transfer path are provided common imaging device, and the driver element that drives this transfer roller.

To transmit each between the too little time interval be set cause multiple supply (multifeed), it is the overlapping transmission of two continuous paper that should be separated to transmit.To transmit each between the too big time interval be set reduce print speed.Therefore, when plurality of sheets of paper was permitted in printing, after picking up a piece of paper, pick up correlation time (the picking up regularly or pick up the stand-by period section) of following a piece of paper controlled by strict.

Especially, traditional double-side impact printing device in this imaging device has than the longer transfer path of simple printing to carry out duplex printing, generally include two independent parts because carry out the transfer path of duplex printing, front print at paper, and another is printed after front print overleaf.In double-side impact printing device, because long transfer path, the transmission of paper often is delayed.

If the transmission of paper is delayed, then printing equipment is determined (jam) to have occurred stopping up and stopped printing.Even printing equipment is determined also not occur stopping up, this delay also can cause multiple supply and the fault during printing.

Summary of the invention

A kind of imaging device and control method thereof were used for during duplex printing if control paper pick-up correlation time during the paper propagation delay.

The other aspect of the inventive concept that this is total and effectiveness part will be illustrated in the following description, and part will be apparent from describe, and perhaps can be known by the practice of this total inventive concept.

Above-mentioned and/or other aspects and the effectiveness of the inventive concept that this is total can realize that this imaging device comprises by a kind of imaging device is provided: a plurality of paper sensors, read the paper that is transmitted along transfer path; Counter transmits the period based on measuring from the read output signal of a plurality of paper sensors, and paper is transmitted during the section at this moment; And controller, if the transmission period of counter measures is different with the benchmark period, the picking up correlation time or show and occurred stopping up of a piece of paper down of the difference control between the period then according to transmission period of measuring and benchmark.

A plurality of paper sensors can comprise and detect the feed in sensor that paper is supplied with, and detect the paper sensor that goes out that paper withdraws from.

Controller can be controlled picking up correlation time of a piece of paper down according to benchmark period and the difference that transmits between the period, and paper is transmitted along a part of transfer path during this transmission period, and wherein image forms on the back side of paper.

No longer than obstruction is set if transmit period and the difference of benchmark between the period time, then controller can be according to the paper pick-up correlation time of this differential delay acquiescence.

Be longer than and stop up the time that is provided with if transmit period and the difference of benchmark between the period, then controller can show and occurred stopping up.

Above-mentioned and/or other aspects and the effectiveness of the inventive concept that this is total also can realize by a kind of method of controlling imaging device is provided, this method comprises: measure in the transmission period of opening during paper is transmitted, the transmission period and the benchmark period of measuring are compared, if the transmission period of measuring is different with the benchmark period, then according to transmission period and the difference of benchmark between the period measured, control is the picking up correlation time or show and occurred stopping up of a piece of paper down.

The transfer path that transmits paper can be divided into first and second portion, and wherein in first, image forms in the front of paper, and at second portion, image forms at the back side of paper.

When paper when second portion is transmitted, when paper during by first, image forms in that paper is positive.

This imaging Method of printing can also comprise: if transmission period and the difference of benchmark between the period measured are provided with the time no longer than obstruction, then according to picking up correlation time that this differential delay is given tacit consent to; Stop up when the time is set if this difference is longer than, then show to have occurred stopping up.

Second portion can extend to a side of developing cell from a side of paper delivery unit, and when paper when second portion is transmitted, measure and transmit the period.

Above-mentioned and/or other aspects and the effectiveness of the inventive concept that this is total also can realize that this device comprises by a kind of imaging device is provided: driver element is used to supply with paper and drive mechanism to form image on the paper of supplying with; And controller, it is according to the transmission period of paper, and control drive unit is with the service time of adjustment paper and the driving time of mechanical hook-up.

Above-mentioned and/or other aspects of this total inventive concept and effectiveness also can realize that this method comprises by the method that provides a kind of recording medium that detects in the imaging device to stop up: the survey record medium is along transmission period that transfer path is transmitted; Determined for first period by more measured transmission period and preset period of time, and determine whether first period be provided with the time greater than default obstruction, and if then detect recording medium and stop up and occur.

Above-mentioned and/or other aspects of this total inventive concept and effectiveness also can by provide a kind of have comprise computer program on it and realize with the computer-readable recording medium of carrying out a kind of method; Wherein this method comprises: the survey record medium is along transmission period that transfer path is transmitted; Determined for first period by the transmission period and the scheduled time slot that compare and measure, and determine whether first period be provided with the time greater than predetermined obstruction, and if then detect recording medium and stop up and occur.

Description of drawings

From the description below in conjunction with each embodiment of each accompanying drawing, these and/or other aspect of the inventive concept that this is total and effectiveness will become obviously and be more readily understood, in the accompanying drawing:

Fig. 1 diagram is according to the configuration of the imaging device of this total inventive concept;

Fig. 2 diagram is according to the configuration of the drive system of the imaging device of the embodiment of this total inventive concept;

Fig. 3 is the control calcspar according to the imaging device of the embodiment of this total inventive concept;

Fig. 4 diagram when normally transmitting paper according to the imaging device of the embodiment of total inventive concept, pick-up roller, feed in sensor and go out the operation timing of paper sensor;

When Fig. 5 diagram postpones the paper transmission when the imaging device according to the embodiment of this total inventive concept, pick-up roller, feed in sensor and go out the operation timing of paper sensor; And

Fig. 6 is the process flow diagram of control according to the method for the imaging device of the embodiment of this total inventive concept.

Embodiment

To illustrate the example of each embodiment in the accompanying drawings in detail with reference to the embodiment of this total inventive concept now, wherein same reference number refers to same element all the time.In order to explain this total inventive concept, each embodiment has been described below with reference to the accompanying drawings.

A kind of imaging device and control method thereof according to the embodiment of this total inventive concept will be described now.

Fig. 1 is the sectional view of diagram according to the structure of a kind of imaging device of the embodiment of this total inventive concept, and Fig. 2 diagram is according to the drive system of imaging device embodiment, Fig. 1 of this total inventive concept.

As shown in fig. 1, this imaging device according to the embodiment of the invention comprises: paper supply unit 10, exposing unit 20, developing cell 30, transfer printing unit 40, fixation unit 50, paper delivery unit 60 and duplex printing unit 70.

Supply plurality of sheets of paper P comprises the paper disc 11 of stacking plurality of sheets of paper P as the paper supply unit 10 of print media, and the spring 12 that flexibly supports this paper disc 11.Be deposited in plurality of sheets of paper in the paper disc 11 and connect a ground by one and pick up, move to developing cell 30 then.

Developing cell 30 comprises: four

development ribbon cartridge

30Y, 30M, 30C and 30K, it comprises the toner of different colours, for example: yellow (Y), pinkish red (M), cyan (C) and black (K) toner.

Development ribbon cartridge

30Y, 30M, 30C and 30K comprise

photoreceptor

31Y, 31M, 31C and 31K, form electrostatic latent image by exposing unit 20 on photosensitive surface, and this exposing unit 20 comprises exposure sources 20Y, 20M, 20C and 20K.

According to the print signal that receives,

photoreceptor

31Y, 31M, 31C and the 31K of development ribbon cartridge arrived in exposure sources 20Y, 20M, 20C and 20K emission corresponding to the light beam of the image information of four kinds of colors (yellow (Y), pinkish red (M), cyan (C) and black (K)).

Each

development ribbon cartridge

30Y, 30M, 30C and 30K comprise: charge image developing toner storage 32, and wherein storage is used for the toner of developed image; Make the power application roll 33 of corresponding

photosensitive body

31Y, 31M, 31C or 31K energising; The latent electrostatic image developing that will form on

photoreceptor

31Y, 31M, 31C and 31K is the developer roll 34 of toner image; And additional toner is to the feed rolls 35 of developer roll 34.

Transfer printing unit 40 will be transferred on the paper at the toner image that develops on the photoreceptor.Transfer printing unit 40 comprises: travelling belt 41, and it moves with the loop that contacts with

photoreceptor

31Y, 31M, 31C and 31K; Drive the driven roller 42 of travelling belt 41; The jockey pulley 43 that keeps the constant-tension of travelling belt 41; And the toner image that will develop on

photoreceptor

31Y, 31M, 31C and 31K is transferred to four transfer rollers 44 of paper.

The paper that 50 pairs of visual pictures of fixation unit have been sent on it applies heat and pressure, makes image be fixed on the paper.Fixation unit 50 comprises: warm-up mill 51, and it has thermal source and has been transferred to paper on it to apply heat to toner; Pressure roll 52, it is provided at warm-up mill 51 opposites, to keep constant photographic fixing pressure between warm-up mill 51 and the pressure roll 52.

Paper delivery unit 60 is discharged into the outside with the paper of printing, and it comprises and accept power and by this power-actuated exit roller 61, and the paper delivery spare roll 62 that is provided at exit roller 61 opposites.

Duplex printing unit 70 transfers back to the upstream extremity of developing cell 30 with this paper after the one side of a piece of paper has been printed, make the two-sided of paper all be printed.Duplex printing unit 70 comprises: form the guide frame 72 in duplex printing path 71, and be provided in the duplex printing path 71 to transmit the duplex printing roller 73 of paper.

Feed in sensor 91 is provided at the upstream extremity of developing cell 30, whether has entered developing cell 30 to read a piece of paper that is picked up by the pick-up roller 13 of paper supply unit 10, and has exported corresponding read output signal then.

Go out paper sensor 92 be provided at paper delivery unit 60 near, be released to outside paper to read, and export corresponding read output signal.

As shown in Figure 2, the imaging device according to present embodiment has driver element 80 to drive above-mentioned each assembly of this equipment.Driver element 80 comprises: the first driver 80a that is driven by first CD-ROM drive motor 81, the second driver 80b that is driven by second CD-ROM drive motor 82, and the 3rd driver 80c that is driven by the 3rd CD-ROM drive motor 83.

First CD-ROM drive motor 81

drives photoreceptor

31Y, 31M, 31C and 31K and the transfer belt 41 of paper supply unit 10, developing cell 30 by power transmission unit (as coupling unit or gear transmission chain).

Second CD-ROM drive motor 82 drives and is provided at ribbon cartridge 30Y, the 30M of the three kinds of colors (yellow, magenta and cyan) except black, each roller among the 30C.

The 3rd CD-ROM drive motor 83 drives each roller that is provided in black development ribbon cartridge 30K, fixation unit 50, paper delivery unit 60 and the duplex printing unit 70.Powerhouse off line tool device 1 is provided between the 3rd CD-ROM drive motor 83 and the black development ribbon cartridge 30K, with the power that transmits the 3rd CD-ROM drive motor 83 off and on to black development ribbon cartridge 30K.One-way clutch 2 is provided between the 3rd CD-ROM drive motor 83 and the fixation unit 50, so that only transmit power in a direction.

As shown in Figure 3, controller 94 control first to the 3rd CD-

ROM drive motor

81,82 and 83 driving operation during duplex printing.

The following operation of controller 94 control: print at every the recto that is connecing a supply by 10 1 of paper supply units, and this paper is sent back the upstream extremity of developing cell 30, then this paper is discharged into the outside by duplex printing path 71.For realizing this control, controller 94 receives from feed in sensor 91 and the read output signal that goes out paper sensor 92.

When a piece of paper is transmitted, owing to slide or disturb the paper propagation delay may appear.This paper is counted by counter 93 time delay, offers controller 94 then.

Controller 94 will storage from paper time delay that counter 93 receives and storer 95 reference time compare, and control is picked up the relevant time (pick up regularly or pick up the stand-by period) to pick up down a piece of paper according to the difference between paper time delay and reference time.Especially, according to the difference between paper time delay and reference time and/or paper supply or the output that goes out

paper sensor

91 or 92, in controller 94 control first to the 3rd CD-

ROM drive motor

81,82 and 83 at least one is so that the service time of the paper time of getting of the following a piece of paper of control or current or following a piece of paper.

Fig. 4 illustrates when the imaging device according to this total inventive concept normally transmits paper, pick-up roller, feed in sensor and go out the operation timing of paper sensor.Fig. 5 illustrates when the imaging device according to this total inventive concept and postpones paper when transmitting, pick-up roller, feed in sensor and go out the operation timing of paper sensor.

As shown in Figure 4, controller 94 drives first to the 3rd CD-

ROM drive motor

81,82 and 83, to start duplex printing.Correspondingly, the pick-up roller 13 of paper supply unit 10 picks up a piece of paper at time tp.From pick-up time tp after the in the past specific time, when this paper when the time, t11 entered into developing cell 30, the read output signal of feed in sensor 91 these paper of output.In response to this read output signal, controller 94 transmits this paper between developing cell 30 and transfer belt 41, make the toner image that develops on photoreceptor be transferred to this recto.When this paper passed through fixation unit 50, the visual picture that is transferred to this paper front was fixed thereon.After the printing of finishing this recto, this paper is passed to paper delivery unit 60.When this paper during, go out the corresponding read output signal of paper sensor 92 outputs by paper delivery unit 60.

The back side of this paper that has been printed when the front through being provided at fixation unit 50 downstreams go out paper sensor 92 time, the rotation of controller 94 counter-rotatings the 3rd CD-ROM drive motor 83.When the 3rd CD-ROM drive motor 83 was rotated in the opposite direction, powerhouse off line tool device 1 was closed the power that is sent to black development ribbon cartridge 30K, and the one-way clutch 2 that is used to drive fixation unit 50 has cut out the power that is sent to fixation unit 50.Then, have only exit roller 61 and duplex printing roller 73 to rotate in the opposite direction, this paper is transferred back to the upstream extremity of developing cell 30 via duplex printing path 71 thus.When this paper was transmitted via duplex printing path 71, counter 93 was measured from the output time t12 that goes out paper sensor 92 to the transmission period ta the output time t13 of feed in sensor 91.

This recto is by after the duplex printing path 71, the special time before entering between travelling belt and

photoreceptor

31Y, 31M, 1C and the 31K, its rotation of reversing once more of the 3rd CD-ROM drive motor 83.At this moment, powerhouse off line tool device 1 transmits the power of the 3rd CD-ROM drive motor 83 to black development ribbon cartridge 30K.

When driving first CD-ROM drive motor 81 and second CD-ROM drive motor 82 and make this paper enter the upstream extremity of developing cell 30, the corresponding read output signal of feed in sensor 91 outputs.At time t13, controller 94 is transmitted this paper between developing cell 30 and transfer belt 41, makes that image forms at the back side of this paper in this paper experience development, transfer printing and fixing.After these back side print procedures of experience, this paper is discharged by paper delivery unit 60.At this moment, when this paper during, go out paper sensor 92 and export corresponding read output signal at time t14 by paper delivery unit 60.From this time t14, controller 94 is waited for and is picked up correlation time (picking up the stand-by period section) td to pick up down a piece of paper.At time t21, instantly a piece of paper pick up stand-by period td section in the past after, controller 94 drives first to the 3rd CD-

ROM drive motor

81,82 and 83 to begin to print down a piece of paper.Correspondingly, pick-up roller 13 picks up and transmits down the upstream extremity of a piece of paper to developing cell 30.After this, controller 94 repeats duplex printing by same operation as described above.

To provide the description of the operation timing of the Fig. 5 that concentrates on the print procedure after the front print now, for the ease of explaining, wherein omitted the description of the process of picking up a piece of paper and printing at this recto.

This recto print finish after, when this paper goes out the read output signal of paper sensor 92 these paper of output during by paper delivery unit 60, in 83 its rotations of counter-rotating of time t12 the 3rd CD-ROM drive motor.Correspondingly, have only exit roller and duplex printing roller, via duplex printing path 71 this paper is transmitted back to the upstream extremity of developing cell 30 thus with opposite spin.

After this, this paper transmits between developing cell 30 and transfer belt 41, makes that image forms at the back side of this paper in paper experience development, transfer printing and fixing.After having experienced these back side print procedures, this paper is released by paper delivery unit 60.

When this paper is transmitted via duplex printing path 71, sometimes this transmission is delayed, what counter 93 was measured enters the transmission period tb of the upstream extremity of developing cell 30 up to this paper at time t13a, the benchmark of being longer than the past when this paper is normally transmitted transmits period ta.Process subsequently is delayed and transmits difference corresponding time delay of the D between period tb and the ta.Correspondingly, from this time t14a, controller 94 is waited for and is picked up correlation time (or pick up and wait for the period) td to pick up down a piece of paper.This waits for the period in time t21a termination, and t21a is the time in the delay of preset time t D 21 time delay.

Although be delayed if transmit, still pick up a piece of paper down in preset time t 21, because the time interval between preceding sheet and back a piece of paper falls short of, multiple supply or obstruction may appear then.Therefore, when be delayed the time t21a of time D the time delay of preset time t 21, controller 94 used pick-up roller 13 to pick up down a piece of paper.

Control method now with reference to Fig. 6 description control imaging Method of printing that total inventive concept is disposed according to basis as mentioned above.

Controller 94 drives first CD-ROM drive motor 81, so that a piece of paper is provided to developing cell 30 (step 101) from paper supply unit 10.

When the read output signal that receives from feed in sensor 91, controller 94 drives second CD-ROM drive motor 82 and the 3rd CD-ROM drive motor 83, to form image (operation 105) at this recto.After front print was finished, this paper was by paper delivery unit 60.At this moment, when when going out paper sensor 92 and receive read output signals, controller 94 deactivations, first motor 81 and second CD-ROM drive motor 82, and the rotation of the 3rd CD-ROM drive motor 83 of reversing.Cause this paper to be transferred back to the upstream extremity (operation 109) of developing cell 30 via duplex printing path 71 like this.At this moment, the transmission period (operation 111) of counter 93 counting paper.

Controller 94 determines whether controller has received the read output signal from feed in sensor 91 then.When controller was received read output signal, whether the transmission period that controller 94 definite counters 93 are measured was longer than the benchmark period (operation 115).Be longer than the benchmark period if determine the transmission period of measuring, then controller 94 determines whether this paper is normally transmitted, and the rotation of the 3rd CD-ROM drive motor 83 of reversing once more, and drive first CD-ROM drive motor 81 and second CD-ROM drive motor 82 and form image (operation 116) with the back side at this paper.During printing overleaf, controller 94 determines whether controller has been received from the read output signal that goes out paper sensor 92 (operation 118).When controller was received read output signal, controller 94 was waited for, up to next the paper pick-up time t21 that arrives acquiescence (operation 120), picks up then and removes a piece of paper.

Alternately, if operate 115 determine it is to transmit the period greater than the benchmark period, then controller 94 determines that transmission is delayed, and determines whether greater than default obstruction is set the time (operation 117) corresponding to the time delay of the difference that transmits period and benchmark period.If be provided with time greater than default obstruction time delay, then controller 94 shows to stop up and occurs, and makes customer inspection stop up and stops printing (operation 119).

If operate 117 determine to be not more than time delay and stop up the time that is provided with, then controller 94 rotation of the 3rd CD-ROM drive motor 83 of reversing once more, and drive first CD-ROM drive motor 81 and second CD-ROM drive motor and 82, form image (operation 123) with the back side at this paper.During printing overleaf, controller 94 determines whether controller has been received from the read output signal that goes out paper sensor 92 (operation 125).When controller was received read output signal, controller 94 waited for, up to next paper pick-up time t21a, consider corresponding to the time delay of transmitting period and the difference of benchmark between the period should the pick-up time, t21a is reset (operation 127).

When the wait period to next paper pick-up stopped, controller 94 was carried out the operation (operation 129) of picking up down a piece of paper from carton.

This total inventive concept can also be presented as the computer-readable code on the computer-readable medium.Computer-readable medium can comprise computer readable recording medium storing program for performing and computer-readable transmission medium.Computer readable recording medium storing program for performing is any data storage device that can store data, and after this these data can be by computer system reads.The example of computer readable recording medium storing program for performing comprises ROM (read-only memory) (ROM), random-access memory (ram), CD-ROM, tape, floppy disk and light data storage device.Computer readable recording medium storing program for performing can also be distributed on the computer system of network coupled, makes computer-readable code be stored and carry out with distributed way.The computer-readable transmission medium can transmit carrier wave or the signal wired or wireless data transmission of the Internet (for example, by).In addition, realize that functional programs, code and the code segment of the inventive concept that this is total can be easily explained by the programmer in field under this total inventive concept.

Apparent from top description, this total inventive concept provides a kind of imaging device and control method thereof, its control is picked up correlation time to pick up down a piece of paper, make when paper is transmitted with the execution duplex printing, even because propagation delay appears in slip or interference, the propagation delay of a piece of paper does not cause negative influence to subsequently process yet, has improved the reliability of imaging device thus.

Although illustrated and described the various embodiment of this total inventive concept, but those skilled in the art should understand that, can change these embodiments and not break away from the principle and the spirit of this total inventive concept, the scope of the inventive concept that basis is total defines in claim and equivalent thereof.

Claims

1. imaging device comprises:

A plurality of paper sensors are used to read a piece of paper that is transmitted along transfer path;

Counter transmits the period based on measuring from the read output signal of these a plurality of paper sensors, and this paper was transmitted during this transmission period; And

Controller, picking up correlation time or showing that obstruction has occurred according to a piece of paper under the difference control between benchmark period and transmission period, this paper is transmitted along a part of this transfer path during this transmission period, and wherein image forms at the back side of this paper

If wherein this transmission period is provided with the time greater than the benchmark period and with poor corresponding time delay between benchmark period and this transmission period no longer than obstruction, then controller picks up poor between the period of this transmission period of constant time lag and benchmark with default, and

If wherein this transmission period is longer than and stops up the time that is provided with greater than the benchmark period and with the poor corresponding time delay between benchmark period and this transmission period, then controller shows to stop up and occurs.

2. imaging device as claimed in claim 1, wherein a plurality of paper sensors comprise:

Detect the feed in sensor of the supply of a piece of paper; And

Detect a piece of paper withdraw from go out paper sensor.

3. imaging device as claimed in claim 2 further comprises:

Have the developing cell of at least one development ribbon cartridge and the paper supply unit of paper supply,

Wherein the upstream extremity at developing cell provides described feed in sensor, and be used for sensing and whether entered developing cell by the paper that paper supply unit picks up, and output corresponding sensing signal.

4. imaging device as claimed in claim 3 further comprises:

Paper delivery unit, the paper that is used for having printed are discharged into the outside,

Wherein saidly go out the paper that paper sensor sensing front has been printed and whether passed the paper delivery unit or be released to the outside by the paper delivery unit, and output corresponding sensing signal.

5. imaging device as claimed in claim 1, wherein the transfer path that is transmitted of this paper is divided into first and second portion, and in this first, image forms at this recto, and at this second portion, image forms at the back side of this paper.

6. imaging device as claimed in claim 5, wherein, when this paper when second portion is transmitted, at this paper by forming image at this recto in the first.

7. imaging device as claimed in claim 6, wherein second portion extends to an end of developing cell from an end of paper delivery unit, and when this paper when second portion is transmitted, measure this transmission period.

8. method of controlling imaging device, this method comprises:

Measure the transmission period during a piece of paper is transmitted;

The transmission period and the benchmark period of measuring are compared; And

According to the benchmark period and transmit difference control the picking up correlation time or show to stop up and occurred of a piece of paper down between the period, this paper is transmitted along a part of this transfer path during this transmissions period, and wherein image is in the formation of the back side of this paper;

If this transmission period is provided with the time greater than the benchmark period and with poor corresponding time delay between benchmark period and this transmission period no longer than obstruction, then pick up poor between the period of this transmission period of constant time lag and benchmark with default; And

If this transmission period is longer than and stops up the time that is provided with greater than the benchmark period and with the poor corresponding time delay between benchmark period and this transmission period, then show to stop up to occur.

9. method as claimed in claim 8, wherein the transfer path that is transmitted of this paper is divided into first and second portion, and in this first, image forms at this recto, and at this second portion, image forms at the back side of this paper.

10. method as claimed in claim 9, wherein, when this paper when second portion is transmitted, at this paper by forming image at this recto in the first.

11. method as claimed in claim 9, wherein second portion extends to an end of developing cell from an end of paper delivery unit, and when this paper when second portion is transmitted, measure this transmission period.